Communications service to the home is provided by cables which extend to a local area and then by individual service cables which extend to each home. In loop distribution plant which employs metallic conductors, a distribution cable may extend to a protected terminal block. From the protected terminal block to each of a plurality of homes extends a drop wire, for example. Such a drop wire is well known and is shown, for example, in U.S. Pat. No. 3,935,369, which issued on Jan. 27, 1976 in the names of E. J. George, et al.
Typically, a protected terminal block includes a plurality of terminal posts and a plurality of terminals. Connected electrically to each of the terminals is a protector which is received in an individual well. Each well is associated with the tip or the ring side of a customer's line. The individual drop wires are connected to the terminal posts. A protector in each well is interposed between a customer's drop wire and the distribution cable. Should the cable be struck by lightning, the protector provides a path to ground thereby avoiding an electrical surge in the drop wires to customers' homes.
In a prior art protected terminal block, bushings in which are received the protectors, are soldered to a plated brass strip which is positioned in a plastic shell. A metallic sleeve which is to extend through the block is soldered to the strip. Module pins are turned threadably into the bushings and extended below the bushings. A metallic terminal which includes two depending terminal tangs is pressed onto each pin. Then the terminal tangs and associates ones of the terminal posts which are supported by another plate are connected together electrically by insulated conductors.
One of each conductor of a pair of insulated conductors is connected to a tang of an associated terminal and the other conductor of the pair of insulated conductors is connected to another tang of an associated terminal. The other tang of each terminal is connected electrically by a strap wire to a post of an associated pair of terminal posts. A drop wire for a particular customer's premises is connected to two posts. Because each side of the line to the customer has a protector therealong, the customer is protected from voltage surges and higher than normal currents.
The wells are formed with the pins in place by introducing a potting compound into the shell. After the potting material cures, the pins are removed by turning them out of the wells. All the pins depend from a plate, which also functions to hold all the terminals. As a result, the individual terminals which are connected to a common ground and associated wiring can not be tested until the pins and the plate are removed. This dictates that the testing is not done until after potting. Consequently, if there are any defects, the completed terminal block has to be discarded because repair of a potted block is not justified economically.
In testing, typically a length of cable is prepared and each end thereof is connected to a terminal block of the above-described configuration. Electrical tests are conducted to insure that continuity exists between the terminal blocks. If the test results are acceptable, the cable is served at an intermediate point to provide two cable lengths, each terminated with a terminal block. If the test results are not acceptable, the cable is severed and the terminal blocks are tested individually. A defective block is discarded because of the difficulty in repairing blocks which have already had a potting compound applied to the terminal posts, terminal tangs and wiring.
Another problem which has surfaced is the intrusion of moisture into the wiring portions of the presently used terminal block. A polyester material has been used to pot the wiring portions of the presently used terminal block. As a result of the moisture intrusion, the insulation resistance of the terminal block is not as high as is desired.
What is sought and what seemingly is not available in the marketplace is a terminal block which allows testing prior to completion of its manufacture to avoid having to dispatch a completed block having a wiring defect. Also what is sought is a terminal block having an insulation resistance which is greater than that of presently used blocks. The sought-after terminal block should be one which is easily manufactured, hopefully at less cost than those presently made.